We plan to study auditory evoked potentials in both clinical neurological disorders and animal experiments to define neural mechanisms of the generation of these potentials. In particular, we will study in experimental animals the role of pontine auditory structures in generating auditory brainstem components using discrete lesion methods. The generation of middle-latency, long-latency, and endogenous components will be examined using electrical recording and lesion methods in monkeys engaged in an auditory discrimination task. The application of auditory evoked potentials to patients with neurological disorders will be for 1) longlatency and endogenous components during the recovery from coma; 2) the effects of task complexity on endogenous components in dementing illnesses and 3) endogenous components during the catagorization of words in patients with aphasia.